The Ozone Symphony
In the grand orchestration that exists in coordinating aircraft flights with satellite paths to gather measurements that are comparable, another method of getting instruments into the air, albeit less technical, completes the harmony: the balloon.
Anne Thompson, a principal investigator for the Arctic Intensive Ozonesonde Network Study (ARCIONS) with the Department of Meteorology at Pennsylvania State University, uses balloons to launch ozonesonde instrument packages into the air to collect atmospheric data.
The ozonesonde is a balloon-borne instrument platform with radio transmitting capabilities that takes direct in-situ measurements of ozone and other atmospheric variables, such as temperature, humidity and pressure. The balloons reach an altitude of between 22 and 25 miles before they explode due to decreased pressure.
"The balloons go all the way to the stratosphere," Thompson says. "We study patterns of tropospheric ozone and determine budgets of how much of that ozone below 10 to 15 kilometers [6 to 9 miles] is from the stratosphere, imported from Asia, or is a result of biomass fires or lightning."
Ozone is measured with an electrochemical concentration cell (ECC), a small sensor developed at the National Oceanic and Atmospheric Administration. The ECC electronically converts readings of air containing ozone into signals compatible with standard meteorological signals, then immediately transmits both the ozone and meteorological data to a ground-based receiving station.
During the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign, Thompson is leading Penn State's Nittany Atmospheric Trailer and Integrated Validation Experiment (NATIVE) air sampling team.
NATIVE is a mobile atmospheric research facility that uses ozonesondes and other instruments to gather column and vertical profiles of ozone. The project was funded specifically as a ground-based complement to NASA field campaigns and to validate Aura satellite observations.
Thompson has used balloon-borne instrumentation in other projects with NASA, including Aura satellite validation. Recently, Thompson's team tested the air in the Mexico City area and Houston, and in Richland, Wash. Pollution in Mexico City affects U.S. Gulf Coast areas including Houston. Richland is affected by pollution coming across the Pacific Ocean from Asia.
The measurements Thompson takes, referred to in the meteorology field as "soundings," will be used in on-going investigations of air quality and pollution transport and deposition in the Northern Hemisphere.
"We have launches from Barrow, Alaska, to Summit, Greenland," Thompson says, "but most of our soundings are in Canada. For ARCTAS, our NATIVE site is in Yellowknife, Northwest Territories. A group of students is taking the soundings there while aircraft sample all over regions affected by fires and imported pollution," she adds. "With so many fires this summer from California and Oregon, ozone from the United States is getting mixed up with ozone from Canadian and Siberian fires."
Thompson sees the Arctic as a very important and sensitive part of the world in terms of atmospheric pollution and is excited to be part of the ARCTAS mission.
"Our participation in ARCTAS benefits the scientific community at large and the university as well," Thompson says. "This will add sites and seasons for us not looked at before."
For missions like ARCTAS, the multivariate platforms used as sources for data collection -- and the data sets themselves -- are the instruments in what Thompson believes creates the triumph that is the ozone symphony.
"Getting extra [balloon] launches coordinated with the aircraft and satellites, and keeping up with all the data, everyone works in harmony, like an orchestra!"
Denise M. Stefula
NASA's Langley Research Center